We are using Fedora Core 3 that came with the hardware form Penguin.
The server is just serving Samba, administrered throgh WebMin and uses ntpd to get the time.
I am tring to make our new server a little more secure and I have a couple of questions.

1. There seem to be several daemons that donn't look real usefull such as canna, iiim, isdn...etc?
I have turned off the daemons I recognise (httpd, hpoj, smartd) but some are hard to goggle. Is there a single place that describes what they are used for or what is dependent on them?

2. I have set up a simple firewall using the setting in the old server, but. that only blocks samba and webmin ports from the internet gateway (i.e protocol is TCP and source is 192.168.1.1 and source port is 137:139 and 10000). Is there some way to figureout how to block everything but wihat is needed for what it is serving and what it needs to get updates? Trial and error is a bit time consuming.

I get that security can be a life times work but the server has to be up by next week. Anything more direct than reading everything would be helpfull.
"Reading everything" is on schedual for next year ;-)

I think I can answer your first question, not sure about the second one.

Check out /etc/services, it lists all protocols, ports and I believe a short description.
If you still don't understand what some specific service is, google it, ask here, or google for "services explained" or something. I'm sure a website has detailed information on any particular service/daemon.